This application claims the priority of German Application No. 196 24 078.6, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a process for correctly sensing an outside temperature.
For sensing the outside temperature in the case of vehicles, temperature sensors are conventionally provided in the engine compartment which emit a signal corresponding to the ambient temperature. The determination of the outside temperature is required, for example, for controlling or regulating a heating or air-conditioning system of a vehicle.
It is a disadvantage in the case of the previously known systems that vehicle influences--particularly the engine heat--do not permit correct sensing of the outside temperature. As a result of the heat emitted by the engine block, the outside temperature sensor, normally housed in the engine compartment, is heated differently depending on the vehicle speed. Accordingly, the temperature sensing is correspondingly falsified.
There is therefore needed a process for correctly sensing the temperature in which errors of the above-mentioned types can be compensated as much as possible.
These needs are met according to the present invention by a process for correctly sensing the outside temperature in the case of a vehicle. The process includes the steps of: 1) sensing the outside temperature via a temperature sensor arranged in a vehicle and forming a corresponding temperature signal; 2) sensing vehicle operating and/or vehicle condition requirements; 3) determining correction values as a function of the vehicle operating and/or vehicle condition requirements; and 4) correcting the temperature signal emitted by the temperature sensor corresponding to the correction values.
In particular, this process ensures an improved outside temperature indication in problem situations, for example, in stop-and-go traffic, when parking the vehicle--for example, in an underground garage--or when taking a driving break while driving on a turnpike, etc. In accordance with the invention, the outside temperature is first sensed conventionally by means of a temperature sensor arranged in a vehicle and a corresponding temperature signal is generated. Then, the vehicle operating and/or vehicle condition requirements--such as the engine oil temperature, the coolant temperature or the vehicle speed--are sensed. By means of these vehicle operating and/or vehicle condition requirements, corresponding correction values are then determined which can be filed, for example, in a table as a function of the respective parameters. By means of the correction values, the temperature signal emitted by the temperature sensor is correspondingly changed so that finally a corrected temperature signal is present which, in fact, corresponds to the correct outside temperature.
The systematic measuring errors are therefore described by a suitable temperature model which is used for calculating the correction. In this case, this process can be used in parallel or supplementary to other constructive solutions.
When establishing the suitable temperature model, the heat transmission resistances between the different components, for example, between the engine and the engine oil or the engine oil and the cooling water system, etc. can be represented correspondingly. In the same manner, the heat capacities inherent in the different components are described by heat capacity model parts. In this manner, a "thermal replacement connection diagram" is obtained which simulates the different heat flows or heat transmissions.
Speed-dependent and vehicle-dependent parameters can be filed in characteristic curves or in tables.
If a minimal temperature is to be indicated in every case, the signal actually generated by the temperature sensor as well as the corrected signal, can be supplied to a device for forming the minimum which selects and transmits the signal corresponding to a minimal temperature.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.